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Milky Way different from most galaxies: study

Milky Way may not be as “typical” as previously thought and studying the universe based on the model of our own galaxy may be misleading, scientists say. The Milky Way, which is home to Earth and its solar system, is host to several dozen smaller galaxy satellites.

These smaller galaxies orbit around the Milky Way and are useful in understanding the Milky Way itself.

Early results from the Satellites Around Galactic Analogs (SAGA) Survey indicate that the Milky Way’s satellites are much more tranquil than other systems of comparable luminosity and environment.

Many satellites of those “sibling” galaxies are actively pumping out new stars, but the Milky Way’s satellites are mostly inert, the researchers found.

This is significant, according to the researchers, because many models for what we know about the universe rely on galaxies behaving in a fashion similar to the Milky Way.

“We use the Milky Way and its surroundings to study absolutely everything,” said Marla Geha from Yale University in the US.

“Hundreds of studies come out every year about dark matter, cosmology, star formation, and galaxy formation, using the Milky Way as a guide. But it is possible that the Milky Way is an outlier,” said Geha, lead author of the study which appears in the Astrophysical Journal.

The SAGA Survey began five years ago with a goal of studying the satellite galaxies around 100 Milky Way siblings.

Thus far it has studied eight other Milky Way sibling systems, which the researchers say is too small of a sample to come to any definitive conclusions. SAGA expects to have studied 25 Milky Way siblings in the next two years.

“Our work puts the Milky Way into a broader context,” said SAGA researcher Risa Wechsler, an astrophysicist at the Stanford University in the US.

“The SAGA Survey will provide a critical new understanding of galaxy formation and of the nature of dark matter,” said Wechsler.